The Possible Dangers of Obstetric Ultrasound

Ultrasound has become so popular in America that you can even get one at the mall. But is ultrasound actually safe? What do we know about ultrasound safety? Screenshot from awombwithaview.com

I’m often asked what the most surprising thing I learned while researching my book, Your Baby, Your Way (originally published under the title The Business of Baby.) Though I had been studying, writing, and talking about birth for over ten years, including as a contributing editor for Mothering magazine and as the author or editor of three other books about babies, my research for this project yielded many surprises. I never considered, for example, that the non-food additives in prenatal vitamins could be contributing to pregnancy symptoms and making women sick. I had no idea how many well designed scientific studies in peer-reviewed journals there were about the benefits of not immediately clamping the cord after a baby is born. And I also did not know that the rise of neonatal ICUs in the United States has led to tremendous profits for hospitals.

But the most surprising research that I came across was about the possible harmful effects of obstetric ultrasound. I was very resistant to the idea that pregnancy ultrasounds may not be safe. Ultrasound safety had not crossed my mind.

I had two ultrasounds during my first pregnancy.

When I read an article about ultrasound safety and why they should be avoided years before I started writing the book, I dismissed it. The idea made me angry … and defensive.

After all, my daughter was just fine, I told myself.

My doctor said they were safe. The doctor would have told us if ultrasound safety was an issue.

I had done nothing wrong.

Of course the ultrasounds I had were warranted and necessary.

Ultrasound safety was not even worth questioning.

Right?

Maybe not.

No proven benefit to prenatal ultrasound

According to ACOG’s Practice Bulletin Number 101, “Ultrasonography in Pregnancy“: “Screening detects multiple gestations, congenital anomalies, and intrauterine growth restriction, but direct health benefits from having this knowledge are currently unproven.” [my emphasis.]

In other words, women who are having low-risk pregnancies and who would choose not abort a fetus that had congenital anomalies have no proven reason to have an ultrasound.

Forget about whether there are issues with ultrasound safety, there are issues with ultrasound necessity.

What multiple scans are good for in these cases is profit for the obstetrician, since prenatal appointments with ultrasound are usually billed to insurance companies for significantly more money than appointments without scans.

Doctors and even midwives often insist on ultrasound for another reason: in the case of a poor outcome for either the mom or the baby, they are concerned that if they did not do multiple prenatal ultrasounds they could get sued and accused of not practicing the standard of care.

“The use of ultrasound for fetal monitoring or any other diagnostic purpose raises some alarming questions that can’t be answered by those who employ it,” wrote Robert S. Mendelsohn, M.D. in his landmark book, How to Raise a Healthy Child In Spite of Your Doctor, first published in 1984. “It is another way in which modern obstetrics violates the medical imperative, passed down by Hippocrates, ‘First, do no harm.'”

Eleven years later, Marsden Wagner, M.D., analyzed the existing scientific studies and concluded that routine ultrasound has been shown to be unnecessary, costly, and of no proven benefit: Ultrasound: More Harm than Good?

As both of these doctors predicted, however, instead of applying appropriate caution to the use of ultrasound, obstetricians and even midwives are using it more than ever today. Most doctors and midwives will be utterly baffled and completely taken aback if you share your concerns with them about ultrasound safety. Nearly 100 percent of pregnant women get prenatal ultrasounds in the United States and Canada, regardless of their risk status. Many are further told that they must have weekly or biweekly scans. One pregnant woman I wrote about reported having over 25 scans.

A mom pregnant with her second child contacted me recently because her doctor is insisting she have an ultrasound once a week. He’s deemed her pregnancy “high-risk” because she is 38 years old and he wants to use the scans to measure the level of amniotic fluid in her uterus in order to schedule an induction.

Yet we know that ultrasound is inaccurate in predicting amniotic fluid levels and the evidence also shows that early induction in the absence of real medical need is associated with increased risk of C-section, maternal mortality, and even fetal demise.

But the problem with ultrasound is not just that it may be unnecessary and may lead to a cascade of other unnecessary interventions. There is also a growing body of evidence that ultrasound exposure itself may be harmful to the developing fetus and a contributing factor in the rise of autism.

One doctor/researcher who has been studying this issue for years, Manuel Casanova, M.D., and his colleague Emily L. Williams, wrote about the possible connection of obstetric ultrasound exposure to brain abnormalities last year.

I asked them permission to reprint their article on my blog. Here it is.

One problem of which we’ve become poignantly aware is that ultrasound safety, especially since the early 1990s, has been deregulated and is nowadays used to excess. We would like to see more research into ultrasound safety, as well as tighter regulations on its use so that the risks don’t outweigh the benefits. We’d also like to clarify that we’re not proposing that ultrasound is “the” cause of autism. What we’re proposing, instead, is that ultrasound may be one of many risk factors for autism for those who have a selective vulnerability.

Many people when they first hear about ultrasound as a possible risk factor in the development of autism think it sounds like pseudoscience.

Who can blame them?

We’ve been subjected to many different hypotheses about what may be causing autism. It seems like everyone is ultimately seeking the “holy grail” of causation. So we’re all skeptical when we hear something new, especially something which seems to contradict our understanding of how we view the world–or in this case, how we perceive the safety of ultrasound.

After all, ultrasound is just a picture, right?

That’s what we in our laboratory used to think until we began studying what mediates the effects of ultrasound. In the following paragraphs we hope to offer a simple explanation on the rather complex effect of ultrasound on the living cell.

Ultrasound refers to sound that has a frequency above that which can be detected by the human ear. Sound itself is the force of pressure through a solid, liquid, or gas; it causes the movement of those particles.

In the case of prenatal ultrasound, the ultrasound transducer emits sonic waves into the abdomen, the sound enters the body including that of the developing embryo/fetus, bounces off the tissue, reflecting back, and that echo is measured by the transducer to form a representative visual image.

Ultrasound is currently used in a variety of ways in medicine and research, including:

1) Production of lesions in neurosurgery, similar to the use of laser;

2) Transcranial (across the skull) stimulation of brain activity, similar to transcranial magnetic stimulation (TMS) or the use of electrodes;

3) Vasodilation, or the widening of blood vessels, which helps in both visualization of the vasculature as well as the delivery of important medications to tissue;

4) Transdermal (across the skin) delivery of medications which would normally be unable to cross the skin barrier;

5) Wound healing, such as on certain bone fractures and ulcers;

6) Purification of foods via its oxidative potential;

7) Purification of metals also due to its oxidative capacity;

8) Transmembrane delivery of nonviral genes into target cells (mainly used in research).

These are just a few examples of how science and medicine apply ultrasound. As you can probably guess by now, given its capacity at different levels of intensity to promote cell growth, cell destruction, alter membrane fluidity (e.g., poke temporary holes in cell membranes), and alter a cell’s activity such as causing a neuron to fire, ultrasound has an incredible range of effects.

It turns out it’s not just a picture after all.

The physical effects of ultrasound include both its pressure on the water within and surrounding a given cell, and through the creation, oscillation (spinning), and implosion of bubbles in that same liquid. The latter is referred to as “cavitation” or the creation of a gaseous cavity within the liquid. Cavitation and noncavitational effects together can poke transient holes in cells, activate certain molecular pathways within those cells, cause temperature increases when the bubble violently implodes, promote the creation of free radicals (oxidation) when that gas escapes into the surrounding medium which can subsequently damage or even kill a cell, can cause general disarray within the cell, and at certain intensities may even promote mutations of DNA.

Most of the deadly effects on cells are generally not seen at diagnostic intensities levels. However, there is still the potential that ultrasound is altering how normal cells develop and behave. That is, it doesn’t kill them, but it may very well change them.

In the case of autism, we frequently find abnormalities in neuron number and growth patterns in the brain. Given that ultrasound has the capacity to promote cellular growth, as well as its overuse in obstetrics and the apparent rising numbers of autism diagnoses, this is a prime area for scientific study.

These are complicated scientific questions that involve a number of different variables and what we have given you here is a gross simplification of our hypothesis. For anyone interested in more detailed accounts, please contact us for further materials and we’d be glad to supply them (see minicolumn.org/people/Casanova).

Back in the 1960s, ’70s, and ’80s, the scientific community was very cautious about using prenatal ultrasound. As much as science knew in the day, they expressed due concern and performed a good number of safety studies. From these studies, they decided that ultrasound was ultimately safe to use in obstetrics. However, science is ever-changing and continually learning more about development. Back in the 1970s, the height of concern over ultrasound was whether it promoted spontaneous abortion or reduced postnatal survival rates, whether it promoted macroscopic growth abnormalities like differences in birth weight and overall size, and whether it caused genetic mutations.

Nowadays, we know much more about the molecular biology of the cell, and more as to how development can be affected in microscopic ways which can have very big effects on behavior. Let’s face it: when a postmortem examination is performed on an autistic person’s brain, usually one of the most striking things about it from a macroscopic level is that there isn’t anything unusual. So the differences in an autistic person’s brain are indeed very subtle; they need to be teased out with various technologies, with a knowledge of the complexity of anatomical, cellular, and molecular biology, and a nuanced understanding of early development. Our science has continued to mature, but unfortunately the early safety studies on ultrasound were never updated to include this new understanding.

It’s time we go back and reassess, with new knowledge, techniques, and technology, whether or not ultrasound is truly as safe as we assume it is.

It’s also time that the regulations on ultrasound safety be refined so that we can be doubly sure we’re not putting our unborn infants at risk, be it for autism or other conditions.

Again, what we want to stress is that we’re not advocating the disuse of ultrasound. It’s an extremely vital and useful tool in medicine. But we are advocating that it be used more wisely. For those who are pregnant, we recommend that ultrasound should not be performed during the first trimester unless it is an at-risk pregnancy, and especially not within the first 8 weeks of gestation. The first 8 weeks is the period when the greatest intensity of growth occurs–and therefore when the greatest damage can be done. Be cautious of early and unnecessary ultrasounds. In addition, don’t use fetal heart rate monitors for private use because these are handheld ultrasounds.

Dr. Manuel Casanova, M.D. did his residency training in neurology and then spent 3 years doing a fellowship in neuropathology at The Johns Hopkins Hospital. During his time at Johns Hopkins, Dr. Casanova was in-charge of Pediatric Neuropathology, a fact which kindled his interest in developmental disorders of the brain. His clinical experience was enhanced by appointments as either a consultant or staff neuropathologist at Sinai Hospital (Maryland), the North Charles Hospital and the D.C. General Hospital. His expertise in the field was recognized by honorary appointments as a Scientific Expert for the Armed Forces Institute of Pathology (AFIP) and as a Professorial Lecturer for the Department of Forensic Science at George Washington University. Dr. Casanova did training in psychiatry at the National Institutes of Mental Health under the tutelage of Drs. Richard Wyatt, Danny Weinberger, and Joel Kleinman. He joined the Medical College of Georgia as a full Professor in 1991 and came to the University of Louisville in 2003 as the Gottfried and Gisela Kolb Endowed Chair in Psychiatry. He has over 200 peer reviewed publications, 71 book chapters and 4 edited books.

Emily L. Williams is a developmental and molecular biologist with ongoing interests in autism research. She studies underlying characteristics common to autism candidate genes as a means to understand why and when they mutate. She is also interested in how the epigenome regulates DNA stability. In addition, she studies the development of cells, how their proliferation and differentiation are regulated, and how these processes might underlie the etiology of autism.

Comments

I can certainly attest to the fact that ultrasounds do not always give an accurate reading on amniotic fluid levels. There’s a great potential for user error. I had an NST at 41 weeks pregnant this spring. 41 weeks was on a Sunday, and I was supposed to go into L&D at my hospital to have it done, as the clinic isn’t open on Sundays. My hospital was on divert (all week! I didn’t get to deliver there at 41+4) and I had my NST at another area hospital. The OB that measured my fluid said that I was at 5 (don’t remember the unit of measurement). An internet search told me that the normal range is 5-25. They wanted me to have another NST at my clinic the next day, and the nurse who did the exam measured my fluids at 15! In 24 hours! Granted, I wanted my fluid levels up, so I drank a lot of water and got some rest that night, but I’m pretty sure that one of those two was off. (I think it was the OB. He wanted me to induce. So did the nurse, actually. She sent me to another hospital for follow-up monitoring.)